KR101560953B1 - Working machine - Google Patents

Abstract

A working machine in which a maximum value of an absorption torque of a hydraulic pump is set to a slightly higher value when a working machine is in a specific state, characterized in that when the operating lever is operated at an intermediate position of a lever stroke, And the operation lever is relatively moved with respect to the gas to adversely affect the operability and at the same time the gas is shaken. When the pulling operation of one or both of the traveling manipulation members 21a and 21b and the boom manipulation member 21e is detected when the maximum absorption torque setting value is the E2 position as the maximum absorption torque setting value with a good fuel consumption, So that the maximum absorption torque setting value is automatically switched to the E1 position.

Description

WORKING MACHINE

The present invention relates to a working machine such as a backhoe.

Conventionally, there is a working machine described in Patent Document 1.

The working machine includes an engine, a variable displacement type hydraulic pump driven by the engine, a maximum absorption torque setting means for setting a maximum absorption torque of the hydraulic pump, a traveling device driven hydraulically by the discharge oil of the hydraulic pump, An upper swing body, a boom, an arm and a bucket, a traveling operation lever for operating these, a swinging arm operating lever, and a boom / bucket operating lever.

In this working machine, it is detected that the working machine is in a specific operating state by detecting the specific operating state of the operating lever, and when the working machine is in a specified state, the maximum value of the absorption torque of the hydraulic pump is changed to a slightly higher value .

Japanese Patent Application Laid-Open No. 2002-295408

When the maximum absorption torque set value is changed, the discharge amount of the hydraulic pump is changed to cause oscillation in the base body. However, since the operation lever is gripped by the operator, when the base body is pivoted when the operation lever is operated at the intermediate position of the lever stroke, There arises a problem that the operation lever is relatively moved with respect to the gas to adversely affect the operability and the gas is shaken.

Therefore, the present invention has as its object to solve the above problems.

Technical solutions made by the present invention for solving the above-mentioned technical problems are characterized by the following points.

According to a first aspect of the present invention, there is provided an engine comprising: an engine; a variable displacement hydraulic pump driven by the engine; a maximum absorption torque setting means for setting a maximum absorption torque of the hydraulic pump; And a boom operating member for operating the boom, wherein the maximum absorption torque setting means includes an E1 position and a maximum absorption torque setting value < RTI ID = 0.0 > And a boom operation detector for detecting a pulling operation of the boom operation member when the boom operation member is operated in the boom up direction, And when the maximum absorption torque set value is the E2 position, the pull operation of one or both of the traveling manipulation member and the boom manipulation member is detected If, it characterized in that the control to automatically switch to the position E1.

In the invention according to claim 2, the traveling operation detector and the boom operation detector detect the pulling operation of the operating member immediately before the operation terminal position of the operating member to be detected.

In the invention according to claim 3, a P position having a maximum absorption torque setting value larger than the E1 position is set in the maximum absorption torque setting means, and the E2 position and the P position can be switched by manual switching means, And is set to the E2 position at the start of the engine.

According to the present invention, the following effects are exhibited.

According to the invention of claim 1, the pull operation of one or both of the traveling manipulation member and the boom manipulation member is detected and automatically switched to the E1 position having the maximum absorption torque setting value larger than the E2 position, Since the operating member is operated to the operating end position, there is no adverse effect on the operability due to the fluctuation of the gas caused by the variation of the discharge amount of the main pump, and the gas is not shaken, and the operability is improved. Further, when the running pull operation and / or the boom lifting pull operation is performed, the maximum absorption torque set value is switched to the torque position which is large, so that the operation of saving energy and the operation of emphasizing speed are simplified and the structure is simplified .

According to the invention of claim 2, by detecting the pulling operation of the operating member immediately before the position of the operating terminal end of the operating member, the response of switching from the E2 position to the E1 position for the pulling operation of the operating member is good.

According to the third aspect of the present invention, basically, since the work is performed in the E2 position in which the output of the hydraulic pump is small, fuel consumption can be suppressed, and when a high working speed and traveling speed are required, By switching to this higher P position, you can work at a higher level of speed.

Further, at the time of pulling operation of the operating member, since the E2 position is automatically switched to the E1 position with the maximum absorption torque set value smaller than the P position, operability and fuel consumption reduction are both achieved.

1 is a side view of a backhoe.
2 is a hydraulic circuit diagram of a backhoe.
3 is a hydraulic circuit diagram of the main part.
4A is a table showing an operation pattern of the switching of the torque position.
4B is a table showing the output pattern of the main pump.
4C is a characteristic diagram of the secondary side pressure of the remote control valve with respect to the operating position of the operating lever.
5 is a hydraulic circuit diagram showing another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1, reference numeral 1 denotes a backhoe (work machine), and the backhoe 1 is mainly composed of a lower traveling body 2 and an upper swinging body 3 mounted on the traveling body 2 have.

The traveling body 2 is constituted by a crawler type traveling device (traveling device) configured to circulate the crawler belt 4 in the circumferential direction by the traveling motors ML and MR composed of hydraulic motors (hydraulic actuators) (5) are provided on both left and right sides of the track frame (6).

A dozer device (7) is provided at the front portion of the track frame (6). The dozer device 7 is provided with a blade 9 on the front end side of a support arm 8 which is pivotally connected to the track frame 6 at the rear end side and which can swing up and down, Is driven to ascend and descend by the expansion and contraction of a dozer cylinder C1 made of a hydraulic cylinder (hydraulic actuator).

The swivel body 3 includes a swivel pedestal 10 mounted on a track frame 6 so as to be rotatable about a pivot axis in the up and down direction and a front working device 11 , And a cabin (12) mounted on the swivel base (10).

The swivel base 10 is provided with an engine 36, a radiator, a fuel tank, a working oil tank, a battery and the like. The swivel table 10 is swiveled by a swivel motor MT comprising a hydraulic motor (hydraulic actuator) do.

A support bracket 13 is provided on the front portion of the swivel base 10 in such a manner as to protrude forward from the swivel base 10 and a swing bracket 14 is provided on the support bracket 13, As shown in Fig. The swing bracket 14 is pivotally driven laterally by a swing cylinder C2 formed of a hydraulic cylinder (hydraulic actuator).

The front working device 11 includes a boom 15 having a base side rotatably pivotally connected to an upper portion of a swing bracket 14 so as to be pivotable about its left and right axes so as to be vertically swingable, An arm 16 which is pivotally supported around the right and left axes so as to be pivotally movable forward and backward, a bucket 17 ) (Work area).

The boom 15 is pivotally driven by a boom cylinder C3 interposed between the boom 15 and the swing bracket 14 and the arm 16 is mounted between the arm 16 and the boom 15 And the bucket 17 is pivotally driven by the bucket cylinder C5 (working cylinder) interposed between the bucket 17 and the arm 16. [

The boom cylinder C3, the arm cylinder C4, and the bucket cylinder C5 are constituted by hydraulic cylinders (hydraulic actuators).

A driver's seat D is provided in the rear portion of the cabin 12. [ An elevation opening 12B capable of being opened and closed by an elevating door 12A is formed in the front portion of the left side surface of the cabin 12 and an unloading lever A arranged to cross the elevating door 12B And is installed so as to be lifted up.

This unloading lever A can be moved to a position where it does not interfere with the lifting and lowering by raising the operator when the operator gets off the car. The operation of the various hydraulic actuators ML, MR, MT, So that it can not be done.

Next, the hydraulic system for operating the various hydraulic actuators ML, MR, MT, C1 to 5 equipped in the backhoe 1 will be described with reference to Figs. 2 and 3. Fig.

The hydraulic system of this backhoe 1 is composed of a control valve CV for controlling the various hydraulic actuators ML, MR, MT and C1 to 5 and a control valve CV for controlling the hydraulic actuators ML, MR, MT, C1 to 5 A main pump 18, and a pilot pump 19 for supplying pilot pressure oil for controlling the pilot switching valve and signal pressure oil such as a pressure detection signal.

The control valve CV includes, in the present embodiment, a first block B1, a bucket control valve V1 for controlling the bucket cylinder C5, a boom control valve V2 for controlling the boom cylinder C3, a first dozer control valve V3 Right drive control valve V4 for controlling the drive motor MR of the left-side drive device 5 on the right side, a second block B2 for pressure oil introduction, and a left-side drive control valve V4 for controlling the drive motor ML of the left- A second dozer control valve V6 for controlling the dozer cylinder C1, an arm control valve V7 for controlling the arm cylinder C4, a swing control valve V8 for controlling the swing motor MT, a swing control valve V9 for controlling the swing cylinder C2 , And the third block B3 are arranged in order (arranged in order from the right side in Fig. 2) and connected to each other.

Each of the control valves V1 to V9 has directional control valves DV1 to DV9 built in the valve body.

Each of the directional control valves DV1 to DV9 switches the direction of pressure reduction relative to the hydraulic actuators ML, MR, MT and C1 to 5 to be controlled. The directional control valves DV1 to SW9 are composed of a linearly spool type switching valve, Which is operated by a pilot switch valve.

The directional control valves DV1 to DV9 of the respective control valves V1 to 9 move the spool in proportion to the operation amount of each of the remote control valves PV1 to PV6 that respectively operate the respective directional control valves DV1 to 9, The hydraulic actuators ML, MR, MT and C1 to 5 to be controlled are supplied with a positive-pressure hydraulic fluid proportional to the actual amount (in other words, the hydraulic actuators ML, ML, MR, MT, and C1 to 5 can be shifted).

Each of the remote control valves PV1 to PV6 is composed of a pilot valve that outputs a pilot pressure proportional to the manipulated variable from the secondary port (output port) and sends it to the pilot pressure receiving portion of the directional control valve DV1 to 8 to be operated.

As the remote control valves PV1 to PV6, a left traveling remote control valve PV1 for operating the direction switching valve DV5 of the left traveling control valve V5 and a right traveling remote control for operating the direction switching valve DV4 of the right traveling control valve V4 Control valve PV2, swing remote control valve PV3 for operating the swing control valve V9 directional control valve DV9, and directional control valve DV3 of the first dozer control valve V3 and the directional control valve DV6 of the second dozer control valve V6 A remote control valve PV4 for the swinging arm for operating the directional control valve DV7 of the arm control valve V7 and a remote control valve PV5 for controlling the direction switching valve DV1 of the bucket control valve V1 And a remote control valve PV6 for the bucket / boom for operating the direction switching valve DV2 of the boom control valve V2.

In the present embodiment, the swing remote control valve PV3 is operated by the operation pedal 20, and the other remote control valves PV1, 2, 4 to 6 are operated by the operation levers 21a to 21e (operating members) , All of which can be operated at a position where the operator is seated in the driver's seat D.

Further, the directional control valve DV3 of the first dozer control valve V3 and the directional control valve DV6 of the second dozer control valve V6 are simultaneously operated (operated simultaneously) by one dozer remote control valve PV3.

The operating levers 21a and 21b (traveling operating members) for operating the left traveling remote control valve PV1 and the right traveling remote control valve PV2 are operated back and forth from the neutral position and the operating levers 21a and 21b The traveling device 2 to be operated is forward-driven, and when it falls backward, the traveling device 2 to be operated is driven backward.

The operation lever 21d, 21e for operating the remote control valve PV5 for swinging and arm and the remote control valve PV6 for bucket and boom can be operated in two directions of forward and backward and left and right directions .

The swing arm remote control valve PV5 operates the directional control valve DV8 of the swing control valve V8 in one direction (for example, in the left-right direction) of the control lever 21d and is operated in the other direction Direction), the directional control valve DV7 of the arm control valve V7 is operated.

The remote control valve PV6 for the bucket / boom operates the directional control valve DV1 of the bucket control valve V1 by the operation of the operation lever 21e (the boom operation member) in one direction (for example, the lateral direction) The directional control valve DV2 of the boom control valve V2 is operated by the operation of the boom control valve V2 (for example, forward and backward directions).

Further, when the operation levers 21d and 21e of the remote control valves PV5 and PV6 are tilted in the oblique direction between the front, rear, left and right sides, a combined operation can be performed.

The first block B1 and the third block B3 contain relief valves V10 and V11, respectively, and the second block B2 contains a travel independent valve V12.

The main pump 18 and the pilot pump 19 are driven by an engine 36 (a drive source such as a motor) mounted on the swivel base 10.

The main pump 18 is constituted by a variable displacement type hydraulic pump having a pump displacement control mechanism such as a swash plate 18a and the like. In the present embodiment, two independent discharge ports 18b, And an inclined plate-type variable displacement pump having a function of a flow rate double pump. Specifically, the main pump 18 employs a split-flow type hydraulic pump having a mechanism for discharging pressure oil alternately from the one piston-cylinder barrel kit to the discharge grooves formed inside and outside the valve plate.

Further, the main pump may be constituted by one or a plurality of single flow type hydraulic pumps.

The discharge circuit X of the main pump 18 is connected to the first main discharge path a connected to the first discharge port 18b of the main pump 18 and to the second discharge port 18c of the main pump 18 And the connected second main discharge path b. Both the first discharge path a and the second discharge path b are all drawn into the second block B2.

From the second block B2, the first discharge path a is switched from the valve body of the right side drive control valve V4, the valve body of the first dozer control valve V3, the valve body of the boom control valve V2 to the valve body of the bucket control valve V1 And reaches the first block B1, and the flow path termination portion is connected to the relief valve V10.

From the first discharge line a to the respective directional control valves DV4, DV3, DV2 and DV1 of the right travel control valve V4, the first dozer control valve V3, the boom control valve V2 and the bucket control valve V1, The pressurized oil is supplied.

From the second block B2, the valve body of the left travel control valve V5, the valve body of the second dozer control valve V6, the valve body of the arm control valve V7, the valve body of the swing control valve V8, And reaches the third block B3 via the valve body of the valve V9, and the flow path termination portion is connected to the relief valve V11.

The second doser control valve V6, the arm control valve V7, the swing control valve V8, and the swing control valve V9 from the second discharge line b to the respective directional control valves DV5, DV6, DV7, DV8 and DV9 of the swing control valve V9 The pressurized oil can be supplied through the pressurized oil branch h.

The control valve CV is provided with drain passages g1 and g2 connected to the relief valves V10 and V11, and the respective drain passages g1 and g2 are joined in the third block B3 and disposed in the tank T.

The first discharge passage a and the second discharge passage b are connected to each other in the second block B2 via a communication passage j across the travel independent valve V12.

The running independent valve V12 is composed of a direct-spool type switching valve and a pilot switching valve which is switched by the pilot pressure.

The travel independent valve V12 is switchable to the merging position 22 allowing the pressure oil flow of the communication path j and the independent supply position 23 interrupting the pressure oil circulation of the communication path j, 22). ≪ / RTI >

The discharge oil of the first discharge port 18b and the discharge oil of the second discharge port 18c are combined and supplied to the directional control valves DV1 to DV9 of the respective control valves V1 to V9 .

When the drive independent valve V12 is switched to the independent supply position 23, the discharge oil of the first discharge port 18b is supplied to the right travel control valve V4, the direction change valves DV4, DV3 of the first dozer control valve V3 And the pressurized oil from the second discharge port 18c can be supplied to the directional control valves V5 and DV6 of the left dosing control valve V5 and the second doser control valve V6.

The pilot pump 19 is constituted by a gear pump of a constant capacity type.

The discharge circuit Y of the pilot pump 19 is constituted by the first to fifth pilot discharges m1, m2, m3, m4 and m5.

The first pilot discharge path m1 has a leading end connected to the discharge port 19a of the pilot pump 19 and a terminating end connected to the primary port 26 of the unloading valve V13.

The second pilot discharge path m2 is connected at its leading end to the first pilot discharge path m1 and at its trailing end to the third pilot discharge path m3 and to the beginning end of the fourth pilot discharge path m4.

The third pilot discharge route m3 and the fourth pilot discharge route m4 are drawn into the second block B2 and the terminating end of the third pilot discharge route m3 is connected to one pressure receiving portion 24a of the travel independent valve V12, And the end portion of the discharge passage m4 is connected to the other pressure receiving portion 24b of the travel independent valve V12.

The fifth pilot injection path m5 is connected to the first pilot discharge path m1 at the leading end and to the relief valve V15 at the terminating end for setting the maximum pressure of the discharge circuit Y of the pilot pump 19. [

The third pilot injection path m3 is connected to the beginning end of the first detection channel r1, and the fourth pilot injection path m4 is connected to the beginning end of the second detection channel r2.

The first detection channel r1 is connected to the direction switching valve DV9 of the swing control valve V9, the direction switching valve DV8 of the swing control valve V8, the direction switching valve DV7 of the arm control valve V7, the direction switching valve DV6 of the second doser control valve V6 Direction control valve V5 Direction switching valve DV5 → right direction control valve V4 direction switching valve DV4 → first doser control valve V3 direction switching valve DV3 → boom control valve V2 direction switching valve DV2 → bucket control valve V1 And is connected to the drain line g1 via the directional control valve DV1.

The second detection passage r2 is connected to a direction switching valve DV6 of the second dozer control valve V6, a direction switching valve DV5 of the left driving control valve V5, a direction switching valve DV4 of the right driving control valve V4, And is connected to the drain passage g1 via the directional control valve DV3.

When the directional control valves DV1 to DV9 of the respective control valves V1 to V9 are neutral, the travel independent valve V12 is held in the merged position 22 by the force of the spring.

When any one of the directional control valves DV6, 7, 5, 8 of the right travel control valve V4, the left travel control valve V5, the first dozer control valve V3, and the second dozer control valve V6 is operated from the neutral position , Pressure is generated in the second detection passage r2, and the travel independent valve V12 is switched from the merging position 22 to the independent supply position 23. [

At this time, any one of the directional control valves DV11, DV10, DV9, DV4, DV3, DV2, DV1 of the bucket control valve V1, the boom control valve V2, the swing control valve V8, the arm control valve V7, When operated, pressure is generated in the first detection passage r1, and the drive independent valve V12 is switched from the independent supply position 23 to the merging position 22.

In addition, the first sensing passage s1 is connected to the third pilot discharge passage m3, the second sensing passage s2 is connected to the fourth pilot discharge passage m4, and the end portions of the first and second sensing passages s1 and s2 are connected to the shuttle valve V14 and a pressure switch 25 is connected to the shuttle valve V14 and the pressure switch 25 is connected to the control device CU for controlling the engine 36 and the main pump 18 through a transmission path .

In the hydraulic system of the present embodiment, an automatic idling control system (AI system) for automatically operating the accelerator device of the engine 36 is provided.

In this auto idling control system, when the directional control valves DV1 to DV9 of the respective control valves V1 to V9 are neutral, no pressure is generated in the first detection passage r1 and the second detection passage r2, In this state, the governor of the engine 36 is automatically controlled by the electric actuator or the like so as to accelerate down to a predetermined idling position without operating the pressure reducing operation. When any one of the directional control valves DV1 to DV9 of the control valves V1 to V9 is operated, pressure is generated in the first detection passage r1 or the second detection passage r2, and this pressure is sensed by the pressure switch 25 The pressure switch 25 operates in a reduced pressure. Then, a command signal is issued to the electric actuator from the control unit CU, and the electric actuator or the like automatically controls the accelerator up to the accelerator position set by the governor.

The primary port (input port) of each of the remote control valves PV1 to PV6 is connected to the pilot port w of the pilot pump channel w via a supply channel k, respectively, to the secondary port 27 of the unloading valve V13. (The remote control valves PV1 to PV6 are connected in parallel to the pilot pump flow path w).

Accordingly, the discharged oil of the pilot pump 19 is sent to the pilot pump flow path w via the unloading valve V13, and pressure oil is supplied from the pilot pump flow path w to the primary port of each of the remote control valves PV1 to PV6.

The unloading valve V13 is provided with a supply position 28 for connecting the first pilot discharge path m1 (the discharge circuit Y of the pilot pump 19) to the start end of the pilot pump flow path w and a second pilot discharge path m1 Which is capable of switching to the unloading position (29) for interrupting the communication between the end of the pilot pump flow path (w) and the start end of the pilot pump flow path (w) .

The unloading valve V13 is urged by the spring 30 in the direction of switching to the unloading position 29 so that the solenoid 31 becomes the unloading position 29 by disengaging the solenoid 31, 28). The solenoid 31 of the unloading valve V13 is excited at a position where the unload lever A disposed on the left side of the driver's seat D is lowered and is disengaged by lifting the unload lever A. [

The unloading valve V13 is switched to the unloading position 29 so that the pressurized oil is not supplied to the respective remote control valves PV1 to PV6, and the hydraulic actuators ML, MR, MT, C1, 5 can not be operated.

In order to improve the responsiveness of the remote control valves PV1 to PV6 for piloting the directional control valves DV1 to DV9 of the control valves V1 to V9 at low temperatures, An warming circuit H for warming the oil in the pilot pump flow channel w is provided.

The warm-up circuit H includes a connection flow path e for connecting the end portion of the pilot pump flow path w and the discharge circuit Y (the second pilot discharge path m2 in the illustrated example) of the pilot pump 19, And a throttling portion (flow rate restricting means) 34.

When warming-up the backhoe 1, the unloading lever A is lifted up to perform the warm-up operation with the unloading valve V13 set to the unloading position 29. [

Then, the oil discharged from the pilot pump 19 first flows from the discharge circuit Y to the end portion of the pilot pump flow path w via the connection flow path e of the warming circuit H. Subsequently, the discharge oil of the pilot pump 19 flowing into the end portion of the pilot pump passage w flows to the start end portion of the pilot pump passage w, and is discharged from the start end portion to the tank T via the unloading valve V13.

That is, the oil sucked from the tank T by the pilot pump 19 passes through the pilot pump passage w and circulates to the tank T, so that the oil in the pilot pump passage w is heated.

Thus, the oil supplied to the primary side port is heated in the vicinity of the primary side port of the remote control valves PV1 to PV6, thereby ensuring the responsiveness of the remote control valves PV1 to PV6 at low temperatures The operability of the remote control valves PV1 to PV6 can be ensured).

Further, the oil discharged from the pilot pump 19 sucked from the tank T is circulated in the pilot pump flow channel w and circulated to the tank T, whereby a sufficient warming effect can be obtained and the warm-up time can be shortened.

Further, since the second pilot discharge path m2 for discharging the discharge oil of the pilot pump 19 to the control valve CV is simultaneously warmed up earlier, the signal circuit of the auto idling control system and the oil of the oil in the first and second detection flow paths r3 and r2 It is effective even in the heat.

The throttle portion 34 provided in the warming circuit H is capable of operating even when the remote control valves PV1 to PV6 are operated even when the unloading valve V13 is switched to the unloading position 29 and the hydraulic actuators ML, MT, C1 to 5 (so that no pressure is generated to pilot the respective directional control valves DV1 to DV9 to the secondary port of the remote control valves PV1 to PV6), and the connection from the discharge circuit Y of the pilot pump 19 Thereby limiting the flow rate of the oil flowing through the flow path e to the pilot pump flow path w.

Therefore, even if the unloading valve V13 is set to the unloading position 29 and the discharged oil of the pilot pump 19 flows through the warming circuit H to the pilot pump flow channel w, the respective remote control valves PV1 to PV6 9 is not operated. In the state where the unloading valve V13 is set at the supply position 28, the discharge oil of the pilot pump 19 flows to the pilot pump flow channel w via the unloading valve V13 as usual, V1 to V9 can be operated, and no waste of the flow rate is generated.

When the secondary pressure is output by operating the remote control valves PV1 to 6, the unloading valve V13 is switched to the supply position 28, and the discharge oil of the pilot pump 19 is supplied to the pilot pump flow passage w from the leading end side The warming circuit H connects the discharge circuit Y of the pilot pump 19 to the end portion of the pilot pump flow path w so that the warming up circuit H can prevent the response delay of the remote control valves PV1 to PV6 .

The flow rate limiting means for limiting the flow rate of the oil flowing from the discharge circuit Y of the pilot pump 19 to the pilot pump flow passage w through the connection flow passage e is constituted by the throttling portion 34 so that it can be provided at low cost.

The pilot pump passage w is normally formed of a hydraulic hose. However, by providing the warming circuit H, the fluidity of the oil in the pilot pump passage w at a low temperature can be improved, The size down of the hose can be achieved and the downsizing of the hose can be easily performed when the hydraulic hose constituting the pilot pump flow path w is disposed.

The flow rate limiting means for limiting the flow rate of the oil flowing from the discharge circuit Y of the pilot pump 19 to the pilot pump flow path w through the connection flow path e is not limited to the above-described throttle portion 34. That is, in the state in which the unloading valve V13 is switched to the unloading position 29, even if the remote control valves PV1 to PV6 are operated, the hydraulic actuators ML, MR, MT and C1 to 5 to be operated do not start As long as it can restrict the flow rate of the oil flowing from the discharge circuit Y of the pilot pump 19 to the pilot pump flow passage w through the connection passage e. The flow rate restriction means may be, for example, Pressure reducing valve 35 may be used.

In this embodiment, the primary port 35a (high-pressure port) of the pressure-reducing valve 35 is connected to the flow passage e1 of the connection passage e on the side of the discharge circuit Y and the secondary port 35b (Reduced pressure side port) is connected to the flow path e2 on the pilot pump flow path w side of the connection flow path e. Further, the pressure reducing valve 35 is pushed in the direction in which the spool is opened by the pressure of the secondary port 35b, and is pressed in the direction in which the spool is closed by the spool spring 35c.

The spring pressure of the spool spring 35c of the pressure reducing valve 35 is controlled such that the pressure of the secondary port 35b of the pressure reducing valve 35 is switched to the unloading position 29, Even when the valves PV1 to 6 are operated, the hydraulic actuators ML, MR, MT, and C1 to 5 to be operated are set to pressures that do not start.

In the hydraulic system of the present embodiment, torque control is performed to limit the maximum absorption torque of the main pump 18 so that the absorption torque of the main pump 18 does not exceed the set value (maximum absorption torque) The set value of the maximum absorption torque can be set and changed to a plurality of set values.

The torque control for limiting the maximum absorption torque of the main pump 18 is performed by controlling the inclination of the main pump 18 to decrease the capacity of the main pump 18 as the discharge pressure of the main pump 18 rises 18a by varying the tilting angle.

3, detection of the discharge pressure of the main pump 18 is performed by discharge pressure detectors 32 and 33 comprising pressure switches respectively connected to the first discharge path a and the second discharge path b . The detection signals of the discharge pressure detectors (32, 33) are transmitted to the control unit CU through the transmission path.

The tilting angle of the swash plate 18a of the main pump 18 is controlled by the regulator R. [

In this embodiment, the regulator R includes a swash plate spring 37 that presses the swash plate 18a, a swash plate actuator 38 that presses the swash plate 18a, and a control unit that controls the pressing force of the swash plate actuator 38 And a swash plate control valve 39. The swash plate 18a of the main pump 18 is controlled by the biasing force of the biasing plate spring 37 and the biasing force of the biasing plate actuator 38. [

The regulator R shown in this embodiment is an example, and a well-known regulator for controlling the swash plate of the variable displacement type hydraulic pump and the like can be employed in addition to the regulator R having the illustrated structure.

The swash plate control valve 39 is constituted by an electromagnetic proportional pressure reducing valve and is controlled by an output current outputted from the control device CU.

The primary port 39a of the swash plate control valve 39 is connected to the discharge circuit Y (fifth pilot discharge path m5 in the figure) of the pilot pump 19 via the communication path q, 39 are connected to the swash plate actuator 38 via the control flow path y.

The swash plate control valve 39 includes a spring 39c for urging the spool in a direction to move the spool toward the communication position 41 for communicating the primary port 39a and the secondary port 39b, (Which generates a force against the urging force of the spring) to shut off the communication between the secondary port 35b and the secondary port 39b and to the blocking position 42 for communicating the secondary port 35b to the tank T (39d).

When the output current (exciting current) output from the control unit CU to the proportional solenoid 39d becomes high, the swash plate control valve 39 is controlled such that the pressure on the secondary side output to the swash plate actuator 38 is reduced ) Is lowered).

A command signal is sent from the control unit CU to the proportional solenoid 39d of the swash plate control valve 39 in accordance with the discharge pressure of the main pump 18 detected by the pressure switches 32 and 33 and input to the control unit CU And the swash plate 18a is controlled so that the maximum absorption torque of the main pump 18 becomes the set maximum absorption torque setting value.

The control device CU has a maximum absorption torque setting means TM for setting a maximum absorption torque setting value of the main pump 18. [

In this maximum absorption torque setting means TM, a plurality of torque positions having different maximum absorption torque setting values are set and can be changed to the maximum absorption torque setting value set at these torque positions.

In the present embodiment, the torque position is determined by the P position (power mode), the E1 position (low economy mode) in which the maximum absorption torque setting value is smaller than the P position, and the E2 position in which the maximum absorption torque setting value is smaller than the E1 position (Maximum absorption torque setting value) of the main pump 18 (high economy mode), the set value of the maximum absorption torque of the main pump 18 can be changed.

4B, in the P position, for example, when the maximum absorption torque set value is close to the maximum torque value of the output torque characteristic of the engine 36 (the maximum torque value does not exceed the maximum torque value In the E1 position, the maximum absorption torque setting value is set to 80% of the maximum absorption torque setting value at the P position, and in the E2 position, the maximum absorption torque setting value is set at the maximum absorption torque setting at the P position It is set to 60% of the value.

The target revolutions of the engine 36 is fixed to a desired target revolving speed and the maximum absorption torque set value at each torque position is not changed.

The switching between the P position and the E2 position is made possible by the manual switching means CM such as a manual switch provided in the vicinity of the driver's seat D. [ In the present embodiment, when the engine 36 is started, it is automatically set to the E2 position, and the switching means CM can switch from the E2 position to the P position and from the P position to the E2 position .

Therefore, basically, the operation is performed in the E2 position where the output of the main pump 18 is small, so that the fuel consumption can be suppressed (fuel economy is good). When a high working speed and running speed are required, the output of the main pump 18 is switched to the high P position, so that the front work device 11, the dozer device 7, the swivel pedestal 10, The swing bracket 14, and the traveling motors ML and MR.

The conversion between the E2 position and the E1 position is done automatically.

In the present embodiment, one or both of the operation levers 21a and 21b for operating the left traveling remote control valve PV1 and the right traveling remote control valve PV2 are pulled back either to the front or rear direction (Stroke end)], or when the operation lever 21e for operating the bucket / boom remote control valve PV6 is fully operated in the boom up direction, or when the left traveling remote control valve PV1, the right traveling remote One or both of the operation levers 21a and 21b for operating the control valve PV2 are fully operated to either the front or rear side and the operation lever 21e for operating the bucket / , It switches from the E2 position to the E1 position.

The pull operation of the operation levers 21a and 21b of the left travel remote control valve PV1 and the right travel remote control valve PV2 is detected by the travel operation detector 43 and the operation lever of the remote control valve PV6 for the bucket / The boom operation detector 44 detects the full operation in the boom up direction of the boom 21e. These detectors 43 and 44 are constituted by pressure switches in the present embodiment.

The travel operation detector 43 is connected to the travel command passage 46 for sending the pilot pressure from the left travel remote control valve PV1, the right travel remote control valve PV2 to the left travel control valve V5, and the right travel control valve V4 Circuit 47 and detects the pressure of the traveling command channel 46 (the secondary pressure of the remote control valves PV1 and PV2) to detect at least one of the two operating levers 21a and 21b for traveling And the pulling operation of the operation levers 21a and 21b is detected.

The boom operation detector 44 is connected to a boom up command line 49 for sending a pilot pressure from the remote control valve PV6 for the bucket / boom to the water pressure portion on the boom up operation side of the direction switching valve DV2 of the boom control valve V2, And detects the pull operation of the operation lever 21e to the boom up side by detecting the pressure of the boom up command channel 49 (the secondary pressure of the port for outputting the boom up command of the remote control valve PV6) .

The traveling operation detector 43 and the boom operation detector 44 are connected to the control unit CU through a transmission line and the detection signals from the traveling operation detector 43 and the boom operation detector 44 are input to the control unit CU.

As shown in Fig. 4A, when the vehicle is switched to the P position, the traveling operation detector 43 and the boom operation detector 44 are in the P position even when the boom operation detector 44 is on or off (operation pattern 1).

When one of the traveling operation detector 43 and the boom operation detector 44 is on and the other is off (operation patterns 2 and 3) or when both are on (when the torque position is the E2 position) In the operation pattern 4), it is switched to the E1 position.

When both of the traveling operation detector 43 and the boom operation detector 44 are OFF, and the torque position is the E2 position, the E2 position is set (operation pattern 5).

Next, detection of the pull operation of the above-described operation levers 21a, 21b, and 21e will be described with reference to FIG. 4C.

Fig. 4C is a characteristic diagram showing changes in the secondary pressure of the remote control valves PV1, PV2 and PV6 with respect to the lever operation positions of the operation levers 21a, 21b and 21e, and the ordinate shows the secondary sides of the remote control valves PV1, PV2, And the lever operating positions of the operating levers 21a, 21b, and 21e are taken on the abscissa.

The pressure on the secondary side increases with the distance from the origin.

The lever operation position is set such that the origin is positioned at the operation starting end position (neutral position, G0 position), which is the start end position of the lever stroke, and is close to the operation end position (G5 position), which is the end position of the lever stroke, Goes.

The operation area of the operation levers 21a, 21b, and 21e is composed of a neutral area 51 (from the G0 position to the G1 position in the drawing) in which the operation object does not operate, (In the example, from the G3 position to the G5 position) near the pulling operation vicinity region 52 and between the neutral region 51 and the pulling operation vicinity region 52 (from the G1 position to the G3 position in the drawing) And an intermediate region 53 as shown in Fig. The intermediate region 53 is divided into a low speed region 53A extending from the G1 position to the G2 position and an intermediate speed region 53B extending from the G2 position to the G3 position.

In the neutral region, since the secondary side pressure is not generated even when the operation levers 21a, 21b, and 21e are operated, the left travel control valve V5, the right travel control valve V4, and the boom control valve V2 do not operate.

The operating levers 21a, 21b, and 21e are operated to the operating terminal position (G5 position) without stopping in the middle of the pulling operation vicinity region 52 without performing the speed adjustment of the operation subject.

In the middle area 53, the operating levers 21a, 21b, and 21e are stopped or changed at an arbitrary position in the area so that the speed of the operation target is adjusted to the desired speed of the operator.

For example, the ratio of the lever stroke of each of the operating regions 51, 53A, 53B,

Neutral region 51: 0% or more and less than 15%

The lower speed region 53A: 15% or more and less than 45%

Middle speed area 53B: 45% or more and less than 75%

Full operation vicinity region 52: 75% to 100%

to be.

4C, when the operation levers 21a, 21b, and 21e are operated from the G0 position to the G1 position, the secondary pressure Pa is generated, and the operation levers 21a, 21b and 21e are operated to increase the secondary pressure from Pa to Pb in proportion to the operation amount of the operation levers 21a, 21b and 21e, and at the secondary pressure Pb, the boom control valve V2, The spools of the control valves V4, DV2, DV4, and DV5 of the left travel control valve V5 are operated to the stroke end.

Further, at the G4 position, the primary side pressure is short cut and flows to the secondary side, and the secondary side pressure rises from Pb to Pc of the maximum output pressure at a time. During operation of the operation levers 21a, 21b, and 21e from the position G4 to the position G5, the secondary pressure is constant at the maximum output pressure Pc.

The traveling operation detector 43 and the boom operation detector 44 detect the secondary side pressure when the operation levers 21a, 21b and 21e are located near the operation terminal end, , 21b, and 21e are detected. Specifically, the operation levers 21a, 21b, and 21e are positioned at the G4 position (near the start position G3 of the pulling operation vicinity region 52), that is, at the operation end positions of the operation levers 21a, 21b, (The minimum pressure Pb of the secondary pressure at the position G4) at the immediately preceding position is detected.

As described above, the operation levers 21a, 21b, and 21e are operated to the operation terminal end position (G5 position) without stopping in the middle of the pulling operation vicinity region 52, ), And it is possible to detect the pulling operation of the operation levers 21a, 21b, and 21e at the G4 position.

In this embodiment, since the pulling operation of the operation levers 21a, 21b, and 21e is detected immediately before the positions of the operation levers 21a, 21b, and 21e, the operation levers 21a, 21b, and 21e ) Is good in response to switching from the E2 position to the E1 position.

In order to detect the pulling operation of the operation levers 21a, 21b and 21e just before being positioned at the operation terminal end position, the traveling operation detector 43 and the boom operation detector 44 are operated in the 2 The secondary side pressure may be detected at a position between the G3 position and the G4 position, or the secondary pressure between Pb and Pc at the G4 position (or 2 Side pressure) may be detected.

The pulling operation of the operation levers 21a, 21b, and 21e may be detected when the operation levers 21a, 21b, and 21e are positioned at the operation termination position, not immediately before being positioned at the operation terminal end position.

In this embodiment, the secondary side pressure is raised from Pb to the maximum output pressure Pc at G4 position at once. However, the operation levers 21a, 21b, and 21e from the G1 position to the G5 position The secondary pressure may be increased in proportion to the operation amount of the secondary pressure.

In the present embodiment, the detection signals of the traveling operation detector 43 and the boom operation detector 44 are transmitted to the control device CU, and when the torque position is the E2 position, the control device CU switches the torque position to the E1 position .

When the control lever 21a, 21b, 21e is returned from the operation terminal end position to the neutral position side and the secondary side pressure of the remote control valves PV1, PV2, PV6 becomes less than Pb, The position is switched.

In addition, switching of the torque position from the E2 position to the E1 position is not performed by an operation other than the pulling operation of the operation levers 21a, 21b, and 21e (operation in the middle area 53).

As described above, when the operation lever 21a or 21b for operating the traveling device 5 is pulled out and / or the boom 15 is operated to operate the boom 15, 21b, and 21e are controlled so as not to be switched by an operation other than the pulling operation of the operation levers 21a, 21b, and 21e, it is possible to reduce the energy saving operation (traveling operation and work operation) (When the boom is pulled up by pulling up the bucket by the boom during steering, spin-turn pull operation, excavation, etc.) during the running straight forward operation, the simplification of the structure is achieved.

Further, it is possible to perform the detection of the operation with an emphasis on the speed by the detection of two points, which is economical and highly reliable.

In addition, since it is automatically switched to the E1 position instead of the P position, both operability and fuel consumption reduction are achieved.

In the prior art, when the maximum absorption torque set value is changed, the discharge amount of the main pump 18 is changed and the base of the backhoe 1 is oscillated. However, the operation levers 21a, 21b, When the base of the backhoe 1 is pivoted by an operation other than the pull operation (operation in the middle area 53), the operation levers 21a, 21b, and 21e are relatively moved with respect to the base body, At the same time, there is a problem that the gas is shaken.

On the other hand, in this embodiment, the operation lever 21a, 21b, or 21e is automatically switched to the E1 position by the pulling operation. In the pulling operation, the operation levers 21a, 21b, 21b and 21e are urged toward the valve body side of the remote control valves PV1, PV2 and PV6 at the operation terminal end positions, and the operation levers 21a, 21b and 21e are operated, There is no adverse effect on the operability due to the oscillation of the gas due to the change in the discharge amount of the main pump 18 and the gas can be smoothly turned without being shaken at the time of steering, .

When the operation levers 21a, 21b and 21e are returned from the operation terminal end position to the intermediate area 53, the torque position is switched from the E1 position to the E2 position, However, in this case, there is no problem since it is during the operation of the operation levers 21a, 21b, and 21e that the operation is switched from the E1 position to the E2 position.

In the prior art, since the maximum absorption torque setting value of the hydraulic pump is switched to a slightly higher set value when the combined operation of the plurality of operation levers is a combined operation of a predetermined combination, the maximum absorption in the neutral region 51 The torque setting value may be switched. In this case, even if the maximum absorption torque setting value is switched and the discharge amount of the main pump 18 is changed, the operability of the operation lever is not adversely affected. However, even in the operation in the low speed region 53A, Operation is performed, so that wasteful fuel consumption occurs.

On the other hand, in the backhoe 1 of the present embodiment, the maximum absorption torque setting value is not switched in the neutral region 51, the low velocity region 53A and the intermediate velocity region 53B (the operating levers 21a and 21b , And 21e), the backhoe 1 can be operated in the E2 position with the maximum absorption torque setting value smaller than the maximum absorption torque setting value in the operation region in which the energy saving is desired.

When the operation of the operating levers 21a, 21b and 21e is detected by detecting the secondary pressure of the remote control valves PV1, PV2 and PV6, the temperature of the oil in the pilot pump passage w becomes The pressure on the secondary side of the remote control valves PV1, PV2, and PV6 is unlikely to increase, and a response delay may occur in switching to the E1 position. However, when the operating levers 21a, 21b, The response of the remote control valves PV1, PV2 and PV6 is good even at a low temperature and the switching to the E1 position at the time of the full operation of the operation levers 21a, 21b, and 21e Of respondents are good.

In this embodiment, three torque positions are provided. However, four or more torque positions may be set (for example, the maximum absorption torque setting value is a torque position between the P position and the E1 position, etc.) .

In the present embodiment, the E1 position is set such that the maximum absorption torque setting value is smaller than the P position set near the maximum torque value of the output torque characteristic of the engine 36. However, the maximum absorption torque setting value at the E1 position The torque setting value may be set near the maximum torque value of the output torque characteristic of the engine 36 (accordingly, the P position becomes the E1 position in this case).

5: Driving device
15: Boom
18: Hydraulic pump (main pump)
21a: absence of traveling device
21b: absence of traveling device
21e: Boom operating member
36: engine
43: traveling operation detector
44: Boom operation detector
TM: Maximum absorption torque setting means
CM: conversion means

Claims (3)

An engine,
A variable displacement hydraulic pump driven by the engine and discharging the discharged oil;
A traveling device that travels by discharge oil discharged from the hydraulic pump;
A traveling operation member that is operated to give an instruction regarding traveling of the traveling device;
A traveling operation detector for detecting a first pulling operation in which the traveling operation member is fully operated,
A boom raised and lowered by discharge oil discharged from the hydraulic pump,
A boom operating member which is operated to give an instruction regarding the rise and fall of the boom,
A boom operation detector for detecting a second pull operation in which the boom operating member is fully operated when the boom operation member is operated so that the boom is raised;
And a control device for controlling the hydraulic pump,
Wherein the control device is capable of setting and changing the set value of the maximum absorption torque of the hydraulic pump and has an E1 position which is a first maximum absorption torque value and an E2 position which is a second maximum absorption torque value which is smaller than the first maximum absorption torque value , The E2 position is set when the first pull operation and the second pull operation are not detected, and the control is automatically switched to the E1 position when either or both of the first pull operation and the second pull operation is detected And the work machine. The method according to claim 1,
The travel operation detector detects the first pull operation by detecting that the travel operation member has passed a predetermined position in front of a position at which the travel operation member is fully operated,
Wherein the boom operation detector detects the second pull operation by detecting that the boom operation member has passed a predetermined position in front of a position at which the boom operation member is operated maximum. 3. The method according to claim 1 or 2,
Further comprising manual switching means for switching between the E2 position and a P position which is a third maximum absorption torque value larger than the first maximum absorption torque value,
Wherein the control device has the P position and is set to the E2 position when the engine is started.

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